This treatment approach uses medicines or drugs to kill cancer cells or slow or prevent their growth. Medical therapies may be used before or after surgery. These are called systemic therapies because the drugs travel throughout the body via the blood to find and attack cancer cells.

Chemotherapy: Generally, chemotherapy kills cancer cells by interrupting and preventing rapidly-dividing cells (like cancer cells) from multiplying. But other rapidly-dividing cells, such as those in the hair follicles and digestive tract may be harmed, causing side effects. The chemotherapy drugs for colorectal cancer include capecitabine, floxuridine, fluorouracil (5-FU), irinotecan hydrochloride, and oxaliplatin. Other agents such as leucovorin calcium and levoleucovorin may be given to boost the effectiveness of 5-FU.

Targeted therapy: These therapies target a specific molecular characteristic of the cancer cell to block its growth and spread. Because targeted therapies aim for the characteristic found only on the cancer cells, they tend to present fewer side effects than some chemotherapy agents. Some targeted therapies for colorectal cancer include: bevacizumab, cetuximab, panitumumab, aflibercept, and regorafenib.